Liner lock knives are a popular style of folding pocket knives. “Liner lock” refers to a blade locking mechanism, which is a side-spring lock that can be opened and closed with one hand without repositioning the knife. The liner lock's lock bar abuts the tang of the blade in the open position to prevent the blade from closing. To release the lock, the user presses the lock bar back toward the handle side, which shifts the lock bar out of the way, enabling the blade to close. In the closed position, the lock bar rests alongside the handle and the blade, typically employing a ball detent to releasably secure the blade in the closed position. One serious disadvantage of liner lock flipper knives is that the user must place his or her fingers in the path of the closing blade in order to disengage the lock bar from the blade. A second disadvantage is it is difficult to make the ball detent strong enough to securely hold the blade closed, but not so strong that the knife is difficult to open.
Button lock knives are another popular style of folding pocket knives. “Button lock” refers to a small push-button that locks the blade in the open position by blocking the blade against a stop such as a pin. By pressing the lock button toward the midline of the knife, the blade is released and is permitted to pivot back to the closed position. The button lock also retains the knife in the closed position, but with much less force than when the blade is open.
Either of these locking mechanisms can be combined with a flipper pocket knife, which refers to the method of folding and unfolding the blade from the handle. These include a flipper tab, which is a protrusion of the blade that is presented normally to the user's index finger when the blade is in the fully closed position. While in this state, the flipper tab enables the user to build enough energy prior to overcoming the resistance provided by the closure retention mechanism that the blade rapidly deploys once the user overcomes the resistance to opening. However, poor flipping technique or an overly weak detent often fail to provide the blade with enough energy to fully open, potentially resulting in unsafe blade opening.
While button lock flipper knives exist, they are not considered optimal or reliable because of weak closed detent retention. The resistance to opening is sufficiently weak that the blade will sometimes release with unintended or underpowered opening force, potentially resulting in unsafe blade opening.
Therefore, a need exists for a new and improved folding knife that can be easily closed with one hand without placing fingers in the path of the closing blade and is tunable to ensure reliable blade opening. In this regard, the various embodiments of the present invention substantially fulfill at least some of these needs. In this respect, the folding knife according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides an apparatus primarily developed for the purpose of being easily closed with one hand without placing fingers in the path of the closing blade and tunable to ensure reliable blade opening.